It is important to have good core samples particularly in offshore work. This is especially true in offshore site investigation which is a prerequisite to foundation analysis for offshore structures, and the like.
Heretofore, piston samplers have been used to obtain offshore core samples. These samplers have required a substantial amount of extraneous equipment such as compensators and bumper subs on the drill string as well as heavy jacks for gripping the sea floor during sampling. There is need therefore for improved samplers having simplicity and durability.